Constant Folding in Query Tree

Implement a constant folding algorithm. Design an algorithm to simplify a query tree that traverses the tree, folds safe nodes, and recursively converts queries into subqueries. The query tree includes the following three components: 1) projection list; 2) predicate list; 3) nested subquery list. Input A JSON object describing a query tree, which includes a projection list, a predicate list, and a nested subquery list. Output Return the simplified query tree. Example Input { "projections": ["col1", "col2 * 2"], "predicates": ["col3 > 5"], "subqueries": [ { "projections": [], "predicates": ["col4 < 10"], "subqueries": [] } ] } Output { "projections": ["col1", "4"], "predicates": ["true"], "subqueries": [] } Example Input {"projections": ["col1", "col2 * 2"], "predicates": ["col3 > 5"], "subqueries": [{"projections": [], "predicates": ["col4 < 10"], "subqueries": []}]}